The only thing that has to happen for infections to reach that level is that malware writers decide smartphone owners are numerous enough and use their phones for transactions valuable enough to be worth the effort to add support for Android and iOS into zero-day malware and exploit kits, according to Trusteer CEO Mickey Boodaei.

Half of all mobile phones in the U.S. are smartphones, and 38 percent of smartphone users have some kind of banking app on the phone that could be targeted by malware.

That's a large audience and a rich potential target, if malware writers can hit the banking connections specifically, rather than the endless streams of chat between users updating each other on their location or asking why someone else is already late.

Boodaei doesn't seem to think the potential infection rate or level of threat is surprising. Plenty of other people do, considering the anxious reactions to report after report in the past few months that more viruses, malware and exploits are surfacing that specifically target iPhones, iPads or Android devices.

It's time to make clear to anyone who carries a smartphone or tablet or laptop something most people who are even slightly geekish already consider too simplistic to have to say out loud:

Computers are vulnerable to viruses, trojans, malware and hacking.

Smartphones are computers.

Therefore, smartphones are vulnerable to malware and hacking.

If you or anyone you know has a smartphone, tablet, music player or other device running iOS, Android or other operating system that allows them to install software, that device and every other one they own can infected by malware and either ruined or made to give valuable personal information away to strangers.

Now that Macs are closer to 10 percent of new machines sold, the pool of victims is a lot bigger and so is the list of viruses designed for Macs.

Smartphones are no different, because they're not actually phones.

Smartphones are tiny computers that are also able to make calls across the same cellular-network data connections they use to download weather reports and compare Angry Bird scores.

Android is a bigger risk, according to a recent report from Symantec, largely because controls on Android apps are so thin that Google has to keep having to pull malware from its apps market.

The Android ecosystem is "a malware cesspool" because users purposely circumvent the security in Android to install new apps, and the Android apps market is largely unfiltered by Google, according to InfoWorld's Galen Gruman.

Apple's overly structured, primly paternalistic Apps Store is more secure because malware is often filtered out along with most of the interesting content.

iPhones, iPads and even iTouch and iPods are vulnerable even so, though there are fewer exploits and code aimed at them specifically because they are a slightly harder target.